Air Force Research Laboratory, Office of Public Affairs
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Airborne Laser Gets Beam-Control System

May 1, 1998
CONTACT: Rich Garcia
PHONE: (505) 846-1911

PALO ALTO, Calif. -- A military and industry team announced this week that a Lockheed Martin-built system here can control a laser beam to the levels needed for the U.S. Air Force’s Airborne Laser to kill attacking missiles.

Successful laboratory tests addressed a key issue in the development of the weapon system: how to point and focus a laser accurately at a hostile missile hundreds of miles away despite vibration in the aircraft and optical turbulence in the atmosphere. All this in a laser-versus-missile battle that could last only a few seconds. The experiments were conducted on a scaled-down demonstrator version of a beam control system that functionally reproduced all elements of the full-scale Airborne Laser beam control system.

These latest tests provided a firm foundation for the Air Force to proceed toward the final design, manufacture and implementation of the Air Force’s aircraft-based theater missile defense system.

The Airborne Laser, or ABL, involves a Boeing 747-400 freighter aircraft that will be modified to carry a high-energy laser. ABL is designed to operate over friendly territory at altitudes above 40,000 feet. There, the aircraft can acquire, track and accurately fire a lethal beam of laser energy on an attacking missile shortly after that missile has been launched. It is during this portion of a missile's flight – the boost phase – when the missile is most vulnerable. By destroying a missile during this phase, there is a strong likelihood that its warhead and debris will fall back on the country that launched it.

"This successful demonstration validates the tracking, pointing hardware and algorithms approach necessary for the ABL mission," said Paul Shattuck, Lockheed Martin Missiles & Space ABL program manager. "This clearly shows the ABL program is ready to proceed into the critical design phase of the Program Definition and Risk Reduction Program."

To ensure the sophisticated beam control flight system was properly designed, Lockheed Martin developed a laboratory demonstrator to simulate the flight hardware as well as the disturbances – such as aircraft platform motion and atmospheric turbulence – to which the hardware must respond.

A major technical challenge for ABL is the long distances that a laser beam must travel through the atmosphere, which causes distortion on that beam. These atmospheric effects were measured by the Air Force and used by Lockheed Martin in its demonstrator to create high-fidelity optical simulations. The data was also used to make atmospheric-simulation optics that permitted reproducible and controllable evaluations of the system’s design.

"This testing approach will produce a final beam control design with greatly diminished risk to performance and cost," explained Paul Shennum, Boeing ABL program manager.

These laboratory tracking demonstrations started as a series of tests that began in 1994 to ensure that scientists could correct for optical distortions in the atmosphere and jitter (movement on the laser beam caused by aircraft vibration). Aircraft-induced vibrations are attenuated using passive isolators for the low frequency components and compensated with fast steering mirrors for the high frequency components. The ability to control aircraft and atmospheric disturbances to the 100 nanoradian level has been demonstrated in scaled testing at the Palo Alto facility.

In the next phase of the laboratory beam control tests, measurements will be made to determine the missile kill range and its variability under a full spectrum of atmospheric turbulence under which ABL may have to operate.

The Airborne Laser program is managed by the ABL System Program Office at Kirtland Air Force Base, N.M. The program office is part of the Space and Missile Systems Center at Los Angeles Air Force Base, Calif.

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